Tie foundation for a railway tie

ABSTRACT

A tie foundation ( 1 ) for a railway tie ( 2 ) having at least a first elastic, preferably elastomer layer ( 3 ) and at least a second elastic, preferably elastomer layer ( 4 ), with a reinforcement layer ( 5 ) being embedded between the first elastic layer ( 3 ) and the second elastic layer ( 4 ), with the second elastic layer ( 4 ) forming an outer surface ( 6 ) of the tie foundation ( 1 ) and the reinforcement layer ( 5 ) comprising a fibrous material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT/AT2009/000077, filed Feb. 26,2009, which claims the benefit of Austrian Application No. A365/2008,filed Mar. 6, 2008, both of which are incorporated herein by referenceas if fully set forth.

BACKGROUND

(a) Field of the Invention

The present invention relates to a tie foundation for a railway tiehaving at least a first elastic, preferably elastomer layer, and atleast a second elastic, preferably elastomer layer, with a reinforcementlayer being embedded between the first elastic layer and the secondelastic layer. Additionally, the invention also relates to a method toproduce a tie foundation as well as an arrangement comprising a railwaytie and a tie foundation.

(b) Description of the State of the Art

As known per se, a tie foundation represents an elastic underlayment,arranged and/or to be arranged underneath a railway tie, which isarranged at said railway tie, e.g., by way of adhesion. The tiefoundation serves to reduce the emission of impact sound created byrailway tracks.

A generic tie foundation is shown e.g., in DE 43 15 215 A1. Here, it issuggested to provide a reinforcement layer between two layers comprisingan elastomer material and to arranged an additional layer comprising anon-woven fabric between the elastomer material and the roadbed suchthat the tie foundation only contacts the roadbed via the exterior layerof non-woven fabric.

The later published AT 505 180 A1 describes a coating material for adirect connection to a concrete part, which comprises a layer made fromat least one polymer having a first surface to contact the concrete partand being connected thereto, with said surface comprising a surfacestructuring. The surface structuring is embodied by at least almostchannel-like and/or pore-shaped recesses and/or by at least almostchannel-like elevations.

From EP 1 445 378 A2 a railway tie is known, with a plastic layer beingmounted to its bottom. In order to connect the plastic layer and theconcrete of the sleeper body a spatially extended grid of threads isembedded both in the sleeper body as well as in the plastic layer.

It has been shown that in the generic tie foundations of prior art thepenetration of the gravel into the tie foundation is insufficientlyprevented, which may lead to an early destruction of the tie foundation.Furthermore, it has shown that frequently problems occur from aninsufficient resistance of the tie foundation against lateraldisplacement.

SUMMARY

The object of the invention is to provide an improvement of generic tiefoundations, which contributes to the avoidance of the above-mentionedproblems or at least to a reduction in them.

This is attained according to the invention by the second elastic layerforming an exterior surface of the tie foundation and the reinforcementlayer comprising a fibrous material.

Therefore, it is provided that the second elastic layer, particularly atleast at the side facing away from and/or opposite the railway tie inthe operational position, forms an exterior surface of the tiefoundation, with the gravel, upon which in the operational position thetie foundation rests together with the railway tie, directly contactingsaid elastic exterior surface of the second layer of the tie foundation.This way, the required resistance against lateral displacement can bemaintained without any problems. The fibrous material of thereinforcement layer also prevents any excessive penetration of thegravel or foundation into the tie foundation such that an earlydestruction of the tie foundation is prevented. By embedding the fibrousmaterial of the reinforcement layer between the first elastic layer andthe second elastic layer the threads of the fibrous material cannot bepushed apart as easily as in a fibrous layer adhered to the exteriorsurface layer of the tie foundation from the bottom such that by theembedding, a reinforcement layer is formed of particular tensilestrength, which prevents any further penetration of the railway gravelinto the tie foundation particularly well.

In order to embody the tensile strength of the reinforcement layer ashigh as possible so that even sharp-edged railway gravel cannotpenetrate the reinforcement layer, it is particularly beneficial for thefibrous material of the reinforcement layer to comprise fibrous threadswhich in addition to the connection by way of embedding between thefirst elastic layer and the second elastic layer are also connected toeach other by at least one additional measure, preferably by way ofknotting or webbing or gluing or welding.

For this purpose, it may be provided that the fibrous material of thereinforcement layer comprises a web or a similar knitted fabric or ismade therefrom, in which as an additional measure the threads areinterwoven and/or looped around each other. An alternative comprisesthat the fibrous material comprises a web or is made therefrom, in whichfibrous threads are linked or knotted to each other. However, it is alsopossible for the fibrous material of the reinforcement layer to compriseat least one web or to be made therefrom, with beneficially hereadditional measures being provided such as an adhesion or welding of thethreads to each other. In correspondingly strong textiles it may besufficient, though, to ensure an appropriately tight interweaving.

The fibrous material of the reinforcement layer may also be made fromdifferent natural or artificial threads, here fiberglass and/or carbonfibers and/or plastic fibers are particularly preferred, preferablypolypropylene or polyamide or polyethylene.

In order to retain the roadbed as effectively as possible, thereinforcement layer should not show any extensively large mesh widthsand/or no extensively large apertures. In this context it is beneficialfor the reinforcement layer to show apertures having an opening width ofno more than 2 mm, preferably no more than 1 mm.

In a tie foundation, explained in greater detail in the following andparticularly easy in its production but also of lasting stability, itmay be provided that the first elastic layer and the second elasticlayer comprise the same material or are made from the same material.This is not mandatory, though, of course the second elastic layer mayalso be made from a material different from the first elastic layer.Beneficially, both the first elastic layer and the second elastic layerare made from an elastomer. Here, foamed elastomers are preferred,particularly closed-pored ones. This may include e.g., polyurethane orcaoutchouc elastomers. In the foamed embodiment they are known aspolyurethane foam or sponge rubber. The caoutchouc materials and/orelastomers may also comprise natural rubber but also artificial rubberproducts. In this context, elastomers generally are understood asform-fixed but elastically deformable materials, which under compressionor tensile stress temporarily deform but when subsequently releasedregain their original undeformed shape. Elastomers may represent bothman-made plastics as well as natural products. Beneficially thematerials of the first elastic layer and/or the second elastic layerhave a density of at least 150 kg/m³ and/or a porosity of at least 10%.A density of these materials ranging from 400 kg/m³ to 900 kg/m³ hasproven particularly beneficial.

In addition to the tie foundation per se, the invention also relates toan arrangement comprising a railway tie and one such tie foundation.Beneficially, here the tie foundation is arranged at least at the bottomof a railway tie facing the ground in the operational position. Ofcourse it is also possible for the tie foundation to be arrangedlaterally at the railway tie, particularly when the railway tie islowered deeper into the roadbed and the gravel thus also laterallycontacts the railway tie.

In order to fasten the tie foundation to the railway tie severalmeasures can be taken, in general. For example, an adhesion or the likeis possible. However, a particularly strong connection is possible, inparticular when the exterior surface of the tie foundation opposite thesecond layer of the tie foundation comprises a connecting layer havingat least one solid material, which has clear spaces open to the exteriorto accept extraneous material between the solid material preferably toaccept concrete from the railway tie. This way it is possible to placethe tie foundation with the connecting layer onto the concrete not yetcompletely cured or onto another not yet cured material of the railwaytie such that the concrete or the other material can penetrate the clearspaces of the connecting layer, during the curing of the railway tieresulting in a material-fitting and/or form-fitting and thusparticularly strong connection between the tie foundation and therailway tie. In this sense, the connecting layer is thereforebeneficially arranged at the side and/or surface of the tie foundationfacing the railway tie in the operational position.

The solid material between which the clear spaces are arranged to acceptthe extraneous material, i.e. particularly from the concrete of therailway tie, can be shaped particularly in the form of bars, burs, andthe like, with beneficially protrusion being provided that can beengaged behind by the material of the railway tie in a form-fittingfashion.

A particularly preferred embodiment provides, however, for the solidmaterial of the connecting layer to comprise a spatially expansive gridmade from threads, with the thickness of the grid and/or the depth ofthe clear spaces open towards the outside amounting to at least 3 times,preferably at least 10 times the thickness of one of the threads. Thisway, any material of the railway ties penetrating into the clear spacescan encompass all threads in a material-fitting and/or form-fittingmanner, resulting in an appropriately stable connection during thecuring of the material. The threads of the grid can here be arrangedirregularly and/or partially be connected to each other and/or projectfrom the first elastic layer in the form of loops. In order to fastenthe connecting layer to the first elastic layer of the tie foundation itis beneficially provided for the connection layer and/or the grid to beembedded in the first elastic layer by at least 20% or at least 40% ofits thickness. By this embedding, a material-fitting and/or form-fittingor fabric-fitting connection is also achieved between the connectionlayer and the first layer.

A preferred method to produce a tie foundation according to theinvention provides for the reinforcement layer to be placed upon afoundation and subsequently a reaction mixture of a material of thefirst elastic layer and the second elastic layer being applied upon thereinforcement layer, preferably at the side facing away from thefoundation and or over the entire surface, and the reinforcement layersubsequently being arranged between the first elastic layer and thesecond elastic layer by way of floating in the reaction mixture whilethe reaction mixture is reacting.

In a tie foundation produced in this manner, the first elastic layer andthe second elastic layer therefore beneficially are made from the samematerial. Embedding the reinforcement layer between these two layerstherefore occurs by floating the reinforcement layer in the reactionmixture before said mixture is finally converted and/or has cured.

In this method, in order to embed a connection layer in the firstelastic layer of the tie foundation, it may be provided that during thereaction of the reaction mixture, preferably in a foaming phase or arising phase of the reaction mixture, the connection layer can beimpressed into the reaction mixture, preferably by at least 20% or atleast 40% of the thickness of the connection layer. Here, it may beprovided that by the impression of the connection layer into thereaction mixture the reinforcement layer may be pressed in the directiontowards the foundation and/or the floating of the reinforcement layer belimited. By the latter measure it can be prevented that thereinforcement layer floats too much in the reaction layer.

An alternate production method provides that initially the first elasticlayer is produced, if applicable with a connection layer arrangedthereat, as a preliminary product and subsequently the reinforcementlayer is applied upon the first elastic layer, and subsequently orsimultaneously the second elastic layer is applied, preferably as areaction mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional details and features of preferred exemplary embodimentvariants of the invention are discernible from the following descriptionof the figures.

Shown are:

FIG. 1 is a side view of an exemplary embodiment of the tie foundationaccording to the invention,

FIG. 2 is a top view of a preferred exemplary embodiment of areinforcement layer prior to its arrangement in the tie foundation,

FIG. 3 is a side view of a railway tie with a tie foundation accordingto the invention,

FIG. 4 is an example for a suitable connection layer,

FIG. 5 is a sketch of the principle of a preferred production method ofa tie foundation, and

FIG. 6 is a graph to explain the foaming phase.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a preferred exemplary embodiment according to FIG. 1, thereinforcement layer 5 is arranged between the first elastic layer 3 andthe second elastic layer 4 of the tie foundation 1. Here, the secondelastic layer 4 forms the lower exterior surface 6 of the tie foundation1, i.e. in the operating position facing away from the railway tieand/or opposite thereto. On the opposite side, i.e. the one pointingtowards the railway tie 2 in the operational position, the tiefoundation 1 is provided with the connection layer 7, which in theexemplary embodiment shown here is embedded in the first elastic layer3. The connecting layer 7 forms a spatially expanded grid made fromthreads 9. The clear spaces 8 are formed between the threads 9, intowhich the material of the railway tie can penetrate in the sense of aform-fitting, material-fitting, or fabric-fitting connection. In orderto fasten it to the first layer 3, the connection layer 7 is embedded byapprox. 40% of its thickness in the first elastic layer 3.Alternatively, it is also possible for the fastening of the connectionlayer 7 e.g., to apply a relatively thick adhesive layer onto theexterior surface of the first elastic layer 3, into which thereinforcement layer 5 can be embedded. In the preferred embodiments thethickness 22 of the first layer 3 ranges from 5 to 15 mm, preferably 5to 6 or 10 to 15 mm. The second elastic layer 4 may be embodiedconsiderably thinner. Its thickness 23 beneficially ranges from 0.2 to 4mm. The thickness of the reinforcement layer 5 embedded between thefirst elastic and the second elastic layer beneficially ranges from 1 to2 mm. The thickness 10 of the connection layer preferably ranges from 5to 15 mm. A thickness of approx. 10 mm is particularly preferred. Theprojection of the connection layer 7 beyond the first layer 3 rangesfrom 3 to 8 mm, particularly preferred from 4 to 5 mm. The thickness ofthe connection layer 7 therefore beneficially ranges from 5 to 10-timesthe thickness of the reinforcement layer 5. The first elastic layer 3 isgenerally thicker than the second elastic layer 4, beneficially it is atleast twice as thick.

FIG. 2 shows in a top view a preferred exemplary embodiment of thereinforcement layer 5 in the form of a net. The fibrous threads 11 ofthis web are interwoven or knotted to each other at their intersections12, resulting in a particularly good tensile strength. The mesh widthand/or the width of the apertures 13 between the individual fibrousthreads 11 beneficially amounts to no more than 1 to 2 mm. Alternativelyto the net shown here, of course textile knitted fabric, such as aninterlaced yarn, can be used. In such reinforcement layers 5 theparticularly high tensile strength is achieved by the interlacing meshof the fibrous threads 11. Alternatively, of course woven materials canalso be used, in which the fibrous threads 11 are interwoven by beinginterlaced with each other. In all above-mentioned exemplary embodimentsthe intersections 12 of the individual fibrous threads can additionallybe adhered or welded to each other. It is even possible to use fibrousnon-woven webs as reinforcement layers, if their threads are connectedin a fixed manner to each other by way of welding, adhesion, felting, orother appropriate measures. The threads and/or fibrous threads 11 of thereinforcement layer 5 are beneficially made from fiberglass and/orcarbon fibers and/or plastic, preferably polypropylene or polyamide orpolyethylene or at least comprise such materials.

FIG. 3 shows a side view of a railway tie 2, with the tie foundation 1according to FIG. 1 being arranged at its bottom. The connection layer 7is therefore embedded in the material of the railway tie 2 as well as inthe material of the tie foundation 1, thus creating a particularlystrong connection. The arrangement of the railway tie 2 and the tiefoundation 1 formed in this manner rests with the exterior surface 6 ofthe second elastic layer 4 on the foundation 14, here having the form ofa roadbed. The railway track is not shown here, which is supported bythe upper edge of the railway tie 2, as known per se.

FIG. 4 shows a perspective view of the connection layer 7 embodied inthe form of a 3-D grid of the exemplary embodiment according to FIG. 4.The grid of the connection layer 7 comprises threads 9 or cordsspatially interlaced with each other preferably comprising a plastic,such as PP (polypropylene), PA (polyamide), or PE (polyethylene) andhaving certain elasticity. Such grids are used for example as drainfilters or geo-grids and are commercially available under those names.The spatial expansion as well as the embodiment of clear spaces 8 isimportant in order to allow a form-fitting or material-fittingconnection to the material of the railway tie 2 as well as to the firstelastic layer 3.

FIG. 5 shows a preferred production method for a tie foundation 1according to the invention. First, the reinforcement layer 5 is placedas the first processing step, e.g., by uncoiling it from a roller 21onto a base 15, preferably spread in a planar fashion. The base 15 ispreferably formed by a conveyer belt or the like, which transports thereinforcement layer 5 to the jet 17 and further in said direction. Thisjet 17 applies a reaction mixture 16 onto the reinforcement layer 5,preferably over the entire surface. The reaction mixture 16 placed uponthe reinforcement layer 5 begins to react or continues its reaction thathad begun earlier. During this reaction period, the reinforcement layer5 rises in the reaction mixture 16. Additionally, during the reaction abeneficial increase in volume of the reaction mixture occurs, e.g., byway of foaming. In order to embed the connection layer 7, a pressureroller 19 is provided in the exemplary embodiment shown here. Thereaction layer 7 is fed via this roller and pressed into the reactionmixture 16 that has not yet fully cured, causing the connection layer 7to be embedded in the first elastic layer 3. The depth of saidimpression of the connection layer 7 is adjusted via the distances ofthe rotary axis 20 of the impression roller 19 and/or the lower surfaceof the impression roller 19 in reference to the base 15. After thefeeding of the connection layer, the reaction of the reaction mixtureends, and here the connection layer 7 can also be used to prevent anyfurther floating of the reinforcement layer 5 in the reaction mixture orto press the reaction layer 5 in the direction of the base 15 such thatthe desired arrangement in the final product is achieved. At the end ofthe reaction process the first elastic layer 3 and the second elasticlayer 4 are produced in the desired thickness comprising the reactionmixture 16. The reinforcement layer 5 is embedded therebetween at thedesired depth. The same applies to the connection layer 7.

FIG. 6 shows a diagram, in which the density D of the reaction mixtureis applied in reference to the reaction period t. The so-called foamingphase 18 is discernible, in which in the reaction mixture a particularlystrong increase in volume occurs, but also a change in viscosity. In themethod shown in FIG. 5 the distance between the jet 17 and theimpression roller 19 should be selected such that, depending on thereaction speed of the reaction mixture 16, the impression of theconnection layer 7 occurs during the foaming phase 18 and/or the risingphase shown in FIG. 6.

LEGEND CONCERNING THE REFERENCE NUMBERS

1 tie foundation

2 railway tie

3 first elastic layer

4 second elastic layer

5 reinforcement layer

6 exterior surface

7 connection layer

8 clear spaces

9 thread

10 thickness

11 fibrous thread

12 intersection

13 aperture

14 ground

15 base

16 reaction mixture

17 jet

18 foaming phase

19 impression roller

20 axis

21 discharge roller

22 thickness

23 thickness

1. A tie foundation (1) for a railway tie (2) comprising at least afirst elastic layer (3) and at least a second elastic layer (4), with areinforcement layer (5) being embedded between the first elastic layer(3) and the second elastic layer (4), and the second elastic layer (4)forms an exterior surface (6) of the tie foundation (1) and thereinforcement layer (5) comprises a fibrous material.
 2. A tiefoundation (1) according to claim 1, wherein the exterior surface of thetie foundation (1) opposite the second layer (4) comprises a connectionlayer (7) having at least one solid material, which between the solidmaterial has clear spaces (8) open towards an outside to acceptextraneous material.
 3. A tie foundation (1) according to claim 2,wherein the solid material of the connection layer (7) comprises aspatially spread grid made from threads (9), with a thickness (10) ofthe grid or a depth of the clear spaces (8) open towards the outside atleast amounts to 3-times a thickness of one of the threads (9).
 4. A tiefoundation (1) according to claim 3, wherein the solid material of theconnection layer (7) comprises a spatially spread grid made from thethreads (9), with the thickness (10) of the grid or the depth of theclear spaces (8) open towards the outside amounts to at least 10-timesthe thickness of one of the threads (9).
 5. A tie foundation (1)according to claim 3, wherein the threads (9) of the grid are arrangedirregularly.
 6. A tie foundation (1) according to claim 3, wherein thethreads (9) of the grid are partially connected to each other.
 7. A tiefoundation (1) according to claim 3, wherein the threads (9) of the gridproject as loops from the first elastic layer (3).
 8. A tie foundation(1) according to claim 2, wherein at least one of the connection layer(7) or the grid are embedded in the first elastic layer (3).
 9. A tiefoundation (1) according to claim 2, wherein at least one of theconnection layer (7) or the grid are embedded in the first elastic layer(3) by at least 20% or at least 40% of a thickness (10) thereof.
 10. Atie foundation (1) according to claim 3, wherein the threads (9) arecomprised of plastic.
 11. A tie foundation (1) according to claim 10,wherein the plastic is polypropylene or polyamide or polyethylene.
 10. Atie foundation (1) according to claim 1, wherein at least the firstelastic layer (3) or at least the second elastic layer (4) comprise afoamed elastomer or are made therefrom.
 13. A tie foundation (1)according to claim 12, wherein the elastomer is a closed-pored.
 14. Atie foundation (1) according to claim 1, wherein at least the firstelastic layer (3) or at least the second elastic layer (4) comprisespolyurethane or a caoutchouc elastomer.
 15. A tie foundation (1)according to claim 1, wherein the first elastic layer (3) and the secondelastic layer (4) comprise the same material.
 16. A tie foundation (1)according to claim 1, wherein the fibrous material of the reinforcementlayer (5) comprises fibrous threads (11), which connect the firstelastic layer (3) and the second elastic layer (4) by way of embedding,and are connected to each other by at least one additional measure. 17.A tie foundation (1) according to claim 16, wherein the additionalmeasure comprises a knotted, adhered or welded connection.
 18. A tiefoundation (1) according to claim 1, wherein the fibrous material of thereinforcement layer (5) comprising at least one of a web, a knittedfabric or a net.
 19. A tie foundation (1) according to claim 18, whereinthe knitted fabric is a non-woven web.
 20. A tie foundation (1)according to claim 1, wherein the fibrous material of the reinforcementlayer (5) comprise fiberglass, carbon fibers or a plastic, or acombination thereof.
 21. A tie foundation (1) according to claim 1,wherein the reinforcement layer (5) comprising apertures (13) which haveopen widths of no more than 2 mm or of no more than 1 mm.
 22. Anarrangement comprising a railway tie (2) and a tie foundation (1)according to claim 1, wherein the tie foundation (1) is arranged atleast at a bottom of the railway tie (2) that is adapted to face aground area (14) in an operational position.
 23. An arrangementaccording to claim 22, wherein an exterior surface of the tie foundation(1) opposite the second layer (4) comprising the connection layer (7)has at least one solid material, which has clear spaces (8) between thesolid material open towards the outside, with material of the railwaytie (2) having penetrated into the clear spaces (8) of the connectionlayer (7) to connect the railway tie (2) to the tie foundation (1). 24.A method for producing a tie foundation (1) comprising at least a firstelastic layer (3) and at least a second elastic layer (4), with areinforcement layer (5) being embedded between the first elastic layer(3) and the second elastic layer (4), and the second elastic layer (4)forms an exterior surface (6) of the tie foundation (1) and thereinforcement layer (5) comprises a fibrous material, the methodcomprising: placing the reinforcement layer (5) a base (15) andsubsequently applying a reaction mixture (16) of a material of the firstelastic layer (3) and the second elastic layer (4) onto thereinforcement layer (5), and subsequently arranging the reinforcementlayer (5) between the first elastic layer (3) and the second elasticlayer (4) during the reaction of the reaction mixture (16) by way offloating it in the reaction mixture (16).
 25. A method according toclaim 24, wherein the reaction mixture (16) of the material of the firstelastic layer (3) and the second elastic layer (4) is applied on thereinforcement layer (5) beginning at a side facing away from the base(15).
 26. A method according to claim 24, wherein the reaction mixture(16) of the material of the first elastic layer (3) and the secondelastic layer (4) is applied over an entire surface of the reinforcementlayer (5.)
 27. A method according to claim 24, further comprising duringthe reaction of the reaction mixture (16), impressing the connectionlayer (7) into the reaction mixture (16).
 28. A method according toclaim 27, further comprising during the reaction of the reaction mixture(16), pressing the connection layer (7) into the reaction mixture (16)in a foaming phase (18) or a rising phase of the reaction mixture (16).29. A method according to claim 27, wherein during the reaction of thereaction mixture (16) the connection layer (7) is pressed into thereaction mixture (16) from a side facing away from the base (15).
 30. Amethod according to claim 27, wherein during the reaction of thereaction mixture (16) the connection layer (7) is pressed into thereaction mixture (16) by at least 20% or by at least 40% of a thickness(10) of the connection layer (7).
 31. A method according to claim 27,wherein due to the impression of the connection layer (7) into thereaction mixture (16) the reaction layer (5) is pressed in a directiontowards the base (15) or the floating of the reinforcement layer (7) islimited.
 32. A method for the production of a tie foundation (1)according to claim 1, further comprising initially producing the firstelastic layer (3) as a preliminary product, and subsequently applyingthe reinforcement layer (5) upon the first elastic layer (3), andsubsequently or simultaneously applying the second elastic layer (4).33. A method according to claim 32, wherein the first elastic layer (3)is produced as a preliminary product using a connection layer (7)arranged thereon.
 34. A method according to claim 32, wherein the secondelastic layer (4) is applied as a reaction mixture.